VENTILATION

1. TS 10–1 VENTILATION The systematic removal of heated air, smoke, and gases from a structure and replacement with cooler, cleaner air

2. TS 10–2 TYPES OF VENTILATION • Vertical • Trench (strip) • Basement • Horizontal • Natural • Forced • Mechanical positive-pressure • Mechanical negative-pressure • Hydraulic

3. TS 10–3 WHY VENTILATE? • Aids in saving lives • Aids in suppressing fire • Aids in reducing property damage

4. TS 10–4 TODAY’S INCREASING NEED FOR VENTILATION • Increased fuel load in all occupancies due to increased use of plastics and other synthetic materials • More products of combustion • More dangerous products of combustion • “Tighter” homes making heat retention greater • Increased insulation • Energy-saving glass • Vapor barriers

5. TS 10–5 ADVANTAGES OF VENTILATION TO RESCUE OPERATIONS • Improves visibility • Allows for faster location of unconscious victims • Simplifies and expedites rescue • Makes conditions safer for firefighter and victims

6. TS 10–6 ADVANTAGES OF VENTILATION TO FIRE ATTACK & EXTINGUISHMENT • Removes smoke, gases, and heat from building • Facilitates entry of firefighters • Reduces obstacles that hinder firefighters • Increases visibility for quicker location of seat of fire

7. TS 10–7 ADVANTAGES OF VENTILATION TO FIRE CONTROL • Reduces mushrooming • Reduces flashover potential • Reduces backdraft potential • Controls fire spread

8. TS 10–8 ADVANTAGES OF VENTILATION TO PROPERTY CONSERVATION • Permits rapid extinguishment • Reduces water, heat, and smoke damage • Confines fire to an area • Allows salvage operations and fire control to take place concurrently

9. VS 10-2 BACKDRAFT INDICATIONS Puffing Smoke Pressurized Smoke Coming From Small Cracks Black Smoke Becoming Dense Yellow-Gray Darkened Windows Walls Too Hot to Touch Rattling Windows Dull Orange Glow of Visible Fire Hot Unbroken Glass

10. TS 10–9 BACKDRAFT PREVENTION Top (vertical) ventilation is the primary method of preventing backdraft.

11. TS 10–11 LIFE SAFETY HAZARDS IN UNVENTILATED BUILDINGS • Obscurity caused by dense smoke • Presence of toxic gases • Lack of oxygen • Presence of flammable gases • Danger of backdraft • Danger of flashover and rollover

12. TS 10–12 FACTORS DETERMINING HORIZONTAL OR VERTICAL VENTILATION • Building type and design • Number and size of wall openings • Number of stories • Number of staircases, shafts, dumbwaiters, ducts, roof openings • Availability of exterior fire escapes • Exposure involvement

13. VS 10-4 VENTILATION PROBLEMS: BASEMENTS • Need to Descend through Heat and Smoke • Blocked or Secured Outside Entrances • Difficulty of Using Natural Ventilation

14. VS 10-5 VENTILATION PROBLEMS: WINDOWLESS BUILDINGS • Late Detection Delaying Ventilation and Creating Backdraft Conditions • Horizontal Ventilation Difficult or Impractical • Usually Require Mechanical Ventilation

15. TS 10–13 VERTICAL FIRE EXTENSION Opening for ventilation purposes before the fire is located may spread the fire to areas that otherwise would not have been affected.

16. TS 10–15 VENTILATION OPENING LOCATION & SIZE FACTORS • Roof type and condition • Effects on fire • Effects on exposures • Attack crew’s readiness • Ability to protect exposures • Size • Availability of natural openings • Fire location • Building construction • Wind direction • Fire phase • Building condition • Building contents

17. VS 10-6 VERTICAL VENTILATION Roof Opening (At least 4’ x 4’ [1.2 m x 1.2 m])

18. TS 10–16 VERTICAL VENTILATION Opening the roof or existing roof openings to allow heated gases and smoke to escape to the atmosphere

19. TS 10–17 PRE-VENTILATION SAFETY PRECAUTIONS • Consider type of building involved. • Consider location, duration, and extent of fire. • Observe safety precautions. • Identify escape routes. • Select place to ventilate. • Move personnel and tools safely to roof.

20. VS 10-7 ROOF TYPES Flat Mansard Shed Butterfly Hip Gable Arch Lantern Gambrel

21. TS 10–29 BASEMENT FIRES • First extension commonly into the attic • May be ventilated in a variety of ways: • Horizontal ventilation through ground-level or below-ground windows • Through interior vertical shafts (stairwells, hoistway shafts, etc.) • Mechanical ventilation through a hole in the floor near a ground-level door or window

22. TS 10–30 ELEVATED STREAMS • Can force air and gases back into building if not used properly • If projected just above the horizontal plane, are effective in subduing sparks and flying brands rising from ventilation opening and in reducing heat of thermal column • Should never be projected through the ventilation hole while firefighters are still inside building

23. VS 10-13 VENTILATION Correct Application Incorrect Application

24. TS 10–31 FACTORS THAT CAN DESTROY VERTICAL VENTILATION EFFECTIVENESS • Improper use of forced ventilation • Excess glass breakage • Fire streams directed into ventilation holes • Skylight breakage • Explosions • Burn-through of the roof, floor, or wall • Additional openings between attack team and upper opening

25. VS 10-14 HORIZONTAL VENTILATION Wind Direction Leeward Windward Fresh Air

26. TS 10–32 HORIZONTAL VENTILATION Venting of heat, smoke, and gases through wall openings such as windows and doors

27. TS 10–34 HOW HORIZONTAL FIRE EXTENSION OCCURS • In all directions by explosion or flash burning of fire gases, flammable vapors, or dust • Through walls and interior partitions by direct flame contact • Through walls by heat conduction through beams, pipes, or other objects that extend through walls • Through wall openings by direct flame contact or by convected air • Through corridors, halls, or passageways by convected air currents, radiation, and flame contact • Through open space by radiated heat or convected air currents

28. TS 10–35a HORIZONTAL EXTENSION KEY POINTS • Wind is helpful but too much wind can be detrimental. • Windward — Side of building the wind is striking • Leeward — Opposite side of building • Horizontal ventilation may block escape of occupants. • There is an ignition hazard to higher portions of the fire building posed by rising heated gases.

29. TS 10–35b HORIZONTAL EXTENSION KEY POINTS (cont.) • Do not open building until charged lines are in place at attack entrance point, where fire might be expected to spread, and in positions to protect exposures. • Take precautions against upsetting horizontal ventilation. • First open a door on leeward side to create a normal process of thermal layering. • Know that opening doors between fire fighting crews and exit point reduces intake of fresh air.

30. VS 10-15 UPSETTING HORIZONTAL VENTILATION

31. TS 10–36 FORCED VENTILATION Ventilation accomplished mechanically (with fans) or hydraulically (with fog streams)

32. TS 10–37 PORTABLE FAN SAFETY MEASURES • Shut down before moving. • Carry by handles. • Clear personnel from area before starting. • Do not place where clothing, draperies, or curtains can be drawn into fan. • Avoid the discharge stream: heat and particles may be projected by venting equipment.

33. TS 10–38 ADVANTAGES OF FORCED VENTILATION • Ensures more positive control of fire • Supplements natural ventilation • Speeds removal of contaminants • Reduces smoke damage • Promotes good public relations

34. TS 10–39 DISADVANTAGES OF FORCED VENTILATION • May cause fire to intensify and spread • Depends upon a power source • Requires special equipment

35. VS 10-16 TYPES OF FORCED VENTILATION Positive Pressure Horizontal Mechanical Hydraulic

36. VS 10-17 FORCED VENTILATION MECHANICAL NEGATIVE PRESSURE Wind Direction Intake Opening (Optional In-Blowing Ejector) Closed Doors Smoke Ejector (Exhaust) Draft Path Salvage Cover Or Tarp Blocking Opening Around Ejector Pressure Inside Building Lower Than Outside Building

37. VS 10-18 FORCED VENTILATION MECHANICAL POSITIVE PRESSURE High Power Fan Exit Opening (Same Size As Entry Opening) Closed Doors Draft Path Pressure Inside Building Higher Than Outside Building Cone Covering Entire Door Opening

38. TS 10–40a ADVANTAGES OF MECHANICAL POSITIVE-PRESSURE VENTILATION • No need to enter smoke-filled environment • Effectively supplements both horizontal and vertical ventilation • Allows for efficient removal of smoke and heat • Does not effect building contents or smoldering debris • Is faster than negative-pressure ventilation

39. TS 10–40b ADVANTAGES OF MECHANICAL POSITIVE-PRESSURE VENTILATION (cont.) • Does not interfere with ingress or egress • Is easier to clean and maintain positive-pressure than negative-pressure fans • Is applicable for all types of structures • Allows for directing heat and smoke away from unburned areas or paths of exit

40. TS 10–41 DISADVANTAGES OF MECHANICAL POSITIVE-PRESSURE VENTILATION • Requires an intact structure • May increase interior levels of carbon monoxide • May extend hidden fires

41. TS 10–42 GUIDELINES FOR EFFECTIVE POSITIVE-PRESSURE VENTILATION • Take advantage of existing wind conditions. • Make certain that cone of air from fan covers the entire entry opening. • Systematically open and close doors or increase the number of fans to reduce size of area being pressurized. • Keep size of exit opening in proportion to the entry opening.

42. VS 10-19 FORCED VENTILATION HYDRAULIC Fog Stream (Covering 85% 90% of Opening Nozzle Tip (At least 2 ft. [0.6m] Back from Opening)

43. TS 10–43 HYDRAULIC VENTILATION • Typically used to clear a structure of heat, smoke, steam, and gases following the initial knockdown of fire • Takes advantage of air that is drawn into the fog stream to help push the products of combustion out of structure • Fog pattern should be wide enough to cover 85 to 90 percent of the window or door opening through which the smoke will be pushed • Nozzle tip should be no closer than 2 feet (0.6 m) from ventilation opening

44. TS 10–44 DISADVANTAGES OF HYDRAULIC VENTILATION • May increase amount of water damage • Will put a drain on available water supply • In freezing temperatures, will increase ice in area surrounding building • Requires nozzle firefighters to remain in heated, contaminated atmosphere throughout operation • Operation may be interrupted if nozzle team has to leave the area